Heat Resistant Bone Screw

Abstract

The present disclosure is directed towards a fastener for implanting into a bone, the fastener comprising a metallic shaft and an outer layer. The outer layer is disposed on an outer surface of the shaft, the outer layer being configured to limit the effect of an electromagnetic field on the metallic shaft, wherein the outer layer includes a threaded portion along its length.

1 . A fastener for implanting into a bone, the fastener comprising:
 a metallic shaft; and   an outer layer disposed on an outer surface of the shaft, the outer layer being configured to limit the effect of an electromagnetic field on the metallic shaft,   wherein the outer layer includes a threaded portion along its length.   
     
     
         2 . The fastener of  claim 1 , wherein the outer layer is a ceramic or polyether ether ketone (PEEK) material. 
     
     
         3 . The fastener of  claim 1 , wherein the outer layer is a coating and has a minimum thickness in a range from about 0.006 inches to about 0.030 inches. 
     
     
         4 . The fastener of  claim 1 , wherein the outer layer is a cannulated sleeve that is removably attachable to the metallic shaft such that the cannulated sleeve encloses at least a majority of the metallic shaft. 
     
     
         5 . The fastener of  claim 4 , wherein the cannulated sleeve is open at a first end of the sleeve and at a second end of the sleeve opposite the first end such that a tip of the metallic shaft is exposed through one of the first and second ends of the sleeve. 
     
     
         6 . The fastener of  claim 4 , wherein the metallic shaft and the cannulated sleeve both include a plurality of flat surfaces meeting at sharp edges such that when the cannulated sleeve is disposed over the metallic shaft, the cannulated sleeve is prevented from rotating relative to the metallic shaft. 
     
     
         7 . The fastener of  claim 1 , wherein the fastener is a bone screw and the metallic shaft includes a head at a proximal end of the metallic shaft. 
     
     
         8 . The fastener of  claim 7 , wherein the threaded portion extends to a distal tip of the fastener. 
     
     
         9 . The fastener of  claim 1 , wherein the outer layer is further configured to prevent radiofrequency exposure to the fastener from heating the metallic shaft. 
     
     
         10 . A fastener for implanting into a bone, comprising:
 a metallic shaft; and   an outer layer disposed on a surface of the metallic shaft, the outer layer being configured to prevent radiofrequency exposure to the fastener from heating the metallic shaft,   wherein the outer layer encloses a majority of the metallic shaft.   
     
     
         11 . The fastener of  claim 10 , wherein a proximal end of the metallic shaft and a distal end of the metallic shaft define respective parts of an outer surface of the fastener and a remaining portion of the metallic shaft therebetween is enclosed by the outer layer. 
     
     
         12 . The fastener of  claim 11 , wherein the fastener is a bone screw and the proximal end of the metallic shaft is a head of the bone screw. 
     
     
         13 . The fastener of  claim 12 , wherein the distal end of the metallic shaft is a distal tip of the bone screw. 
     
     
         14 . The fastener of  claim 10 , wherein the outer layer is a ceramic or polyether ether ketone (PEEK) material. 
     
     
         15 . The fastener of  claim 10 , wherein the outer layer is a coating and has a minimum thickness in a range from about 0.006 inches to about 0.030 inches. 
     
     
         16 . The fastener of  claim 10 , wherein the outer layer is a cannulated sleeve that is removably attachable to the metallic shaft. 
     
     
         17 . The fastener of  claim 16 , wherein the cannulated sleeve is open at a first end of the sleeve and at a second end of the sleeve opposite the first end such that a tip of the metallic shaft is exposed through one of the first and second ends of the sleeve. 
     
     
         18 . The fastener of  claim 16 , wherein the metallic shaft and the cannulated sleeve both include a plurality of flat surfaces meeting at sharp edges such that when the cannulated sleeve is disposed over the metallic shaft, the cannulated sleeve is prevented from rotating relative to the metallic shaft. 
     
     
         19 . The fastener of  claim 10 , wherein the outer layer is further configured to limit the effect of an electromagnetic field on the metallic shaft. 
     
     
         20 . A method of using an implant in a surgical procedure comprising:
 anchoring a bone screw in a bone of a patient or in a prosthesis disposed in the patient, the bone screw including a metallic shaft and a ceramic or polyether ether ketone (PEEK) outer layer enclosing an outer surface of the metallic shaft; and   conducting a magnetic resonance imaging (MRI) scan of the patient, wherein the ceramic or PEEK coating reduces temperature changes in the metallic shaft due to the scan that would occur without the ceramic or PEEK coating.